I need to make a couple trim pieces out of 3/4 x 3/16 half oval brass. It has to be bent on edge into about a 7" radius. Rolling seems to be the best way to do it and I'm thinking I am going to have to make the dies. How critical is the diameter of the die in rolling something like this? Seems like the bigger the better, up to whatever will fit in the roller, but really don't know.
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Rolling flat brass on edge
- Thread starter David M
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Ries
Diamond
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- Mar 15, 2004
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- Edison Washington USA
bending half oval the hard way is a challenge.
When you roll a flat bar into a curve the hard way, the physics are inescapable- Its whats called constant volume metalworking.
(there are three kinds of metalworking- subtractive, which is when you cut metal away, additive, which is when you weld new metal on, and constant volume- forging, bending, and casting, where you rearrange the same volume of metal)
To change a straight flat bar into a curve, you inevitably thin out the outer edge, and thicken the inner edge.
How noticeable this is depends on the size of the material- but its always there.
So rolling this bar will make the outside edge thinner, and the inside edge thicker. With ordinary flat bar, you can sand the inside down, and its less noticeable.
But with half oval, my guess is you are gonna see this.
The actual diameter of the rolls is much less important than the profile of the rolls.
To roll a half oval the hard way, you need rolls that are cut to support half the profile on each of the three rolls. Usually these would be made of UMHW, or Delrin, or a similar tough plastic.
And, usually, you would do multiple passes, each a bit more than the last. That depends, however, on the hardness and ductility of the metal. I roll a lot of steel and aluminum, both of which are relatively forgiving, but some aluminums will crack or break if you try too much in one pass. Other materials may work harden, meaning you need to do it in as few passes as possible, or anneal between passes.
"brass" is not a single definable thing- its a nickname for a family of copper alloys, which act differently depending on composition.
Is this for an automotive app, where it needs to be perfect? If so, I would seriously consider casting, then machining.
It can be rolled, but its not going to look like it was bugatti quality.
One thing I would consider if you really need perfect cosmetics, is roll a piece of rectangular flat bar to the needed radius, then mill the profile in. Or, if you are feeling snappy, just hand sand it in- thats how the old french body guys would have done it.
I would probably turn down a job like this, but if it was for a project of my own, I would try forging the profile oversize from a forgeable copper alloy, say silicon bronze, using dies I machined for the power hammer, then roll it, then try milling it to near net on the rotab on the vertical mill, then hand sand it to final profile with flap discs and random orbits.
Or, maybe just roll flat bar, then mill and sand. I usually do much bigger stuff, and the forging is worth it when I do 1/2" x 2" Stainless this way- which I did, a couple years ago, for a big railing job.
If it was easy, everybody would be doing it.
Or, bite the bullet, and pay somebody to CNC mill em from a big chunk of brass plate. Definitely the easiest, fastest, and best looking, it just costs more and requires 21st century technology.
When you roll a flat bar into a curve the hard way, the physics are inescapable- Its whats called constant volume metalworking.
(there are three kinds of metalworking- subtractive, which is when you cut metal away, additive, which is when you weld new metal on, and constant volume- forging, bending, and casting, where you rearrange the same volume of metal)
To change a straight flat bar into a curve, you inevitably thin out the outer edge, and thicken the inner edge.
How noticeable this is depends on the size of the material- but its always there.
So rolling this bar will make the outside edge thinner, and the inside edge thicker. With ordinary flat bar, you can sand the inside down, and its less noticeable.
But with half oval, my guess is you are gonna see this.
The actual diameter of the rolls is much less important than the profile of the rolls.
To roll a half oval the hard way, you need rolls that are cut to support half the profile on each of the three rolls. Usually these would be made of UMHW, or Delrin, or a similar tough plastic.
And, usually, you would do multiple passes, each a bit more than the last. That depends, however, on the hardness and ductility of the metal. I roll a lot of steel and aluminum, both of which are relatively forgiving, but some aluminums will crack or break if you try too much in one pass. Other materials may work harden, meaning you need to do it in as few passes as possible, or anneal between passes.
"brass" is not a single definable thing- its a nickname for a family of copper alloys, which act differently depending on composition.
Is this for an automotive app, where it needs to be perfect? If so, I would seriously consider casting, then machining.
It can be rolled, but its not going to look like it was bugatti quality.
One thing I would consider if you really need perfect cosmetics, is roll a piece of rectangular flat bar to the needed radius, then mill the profile in. Or, if you are feeling snappy, just hand sand it in- thats how the old french body guys would have done it.
I would probably turn down a job like this, but if it was for a project of my own, I would try forging the profile oversize from a forgeable copper alloy, say silicon bronze, using dies I machined for the power hammer, then roll it, then try milling it to near net on the rotab on the vertical mill, then hand sand it to final profile with flap discs and random orbits.
Or, maybe just roll flat bar, then mill and sand. I usually do much bigger stuff, and the forging is worth it when I do 1/2" x 2" Stainless this way- which I did, a couple years ago, for a big railing job.
If it was easy, everybody would be doing it.
Or, bite the bullet, and pay somebody to CNC mill em from a big chunk of brass plate. Definitely the easiest, fastest, and best looking, it just costs more and requires 21st century technology.
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EmGo
Diamond
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- Over the River and Through the Woods
L Vanice
Diamond
- Joined
- Feb 8, 2006
- Location
- Fort Wayne, IN
"Or, bite the bullet, and pay somebody to CNC mill em from a big chunk of brass plate. Definitely the easiest, fastest, and best looking, it just costs more and requires 21st century technology."
Or do it on a big lathe, whether CNC or antique. Brass is very easy to turn by hand on a wood lathe, as I discovered in 1954 when I got my first lathe. An oval shape is easy to cut with hand-held turning tools, or pretty easy to hand grind into a HSS form tool for an engine lathe. Doing an oval on CNC is almost like cheating. The problem I see is getting and holding the big chunk of brass while machining it. Short slice of 14" or 15" diameter heavy wall brass tubing? Roll up a piece of rectangular brass into a circle and solder it to a flat steel plate for mounting to a faceplate? Hope the budget is adequate.
Larry
Or do it on a big lathe, whether CNC or antique. Brass is very easy to turn by hand on a wood lathe, as I discovered in 1954 when I got my first lathe. An oval shape is easy to cut with hand-held turning tools, or pretty easy to hand grind into a HSS form tool for an engine lathe. Doing an oval on CNC is almost like cheating. The problem I see is getting and holding the big chunk of brass while machining it. Short slice of 14" or 15" diameter heavy wall brass tubing? Roll up a piece of rectangular brass into a circle and solder it to a flat steel plate for mounting to a faceplate? Hope the budget is adequate.
Larry
Ries
Diamond
- Joined
- Mar 15, 2004
- Location
- Edison Washington USA
This is assuming its just a section of a circle. If it has straight sections leading in and out, or is not a constant radius, then you would still need to do more massaging.
richard newman
Titanium
- Joined
- Jul 28, 2006
- Location
- rochester, ny
I roll, braze and turn 12" diameter brass rings on my 17" lathe fairly often. I use form tools ground in hss.
As Larry says, brass can also be turned with hand tools. I like to use zero rake, scraping tools to avoid grabbing. I discovered this as a woodworker before I knew how to machine metal, maybe from reading the Holtzapffel books.
If you have a mill, but no lathe, you could mount the rolled blank on a rotary table and modify a hss router bit to your profile. Rabbeting cutters make handy blanks for custom shapes.
As Larry says, brass can also be turned with hand tools. I like to use zero rake, scraping tools to avoid grabbing. I discovered this as a woodworker before I knew how to machine metal, maybe from reading the Holtzapffel books.
If you have a mill, but no lathe, you could mount the rolled blank on a rotary table and modify a hss router bit to your profile. Rabbeting cutters make handy blanks for custom shapes.
I should have put a picture in the original post. These are cockpit trim pieces for a 1937 Gar Wood that I am building. There are 12 of them total, one for each corner of each cockpit. My chrome guy was good enough to ruin two of them for me so now I get to figure out how to replace them. I appreciate the responses, but I have to say, so far it's not been encouraging.
memphisjed
Stainless
- Joined
- Jan 21, 2019
- Location
- Memphis
Anything but brass. Roll a half round and mill/grind the bottom off. The thinning and upsetting is more noticeable the further away from bend centerline, when you grind the bottom you remove these areas.
L Vanice
Diamond
- Joined
- Feb 8, 2006
- Location
- Fort Wayne, IN
I suppose boat parts are best made of brass or stainless and brass is easier to work. It is easy to silver braze straight pieces to the quarter circle pieces.
sierraboat.com
Larry
1937 Gar Wood 25ft Triple Cockpit - "Midnight Thunder" - Sierra Boat Co.
1937 Gar Wood 25ft Triple Cockpit. Midnight Thunder is one of only three 25-footers equipped with the largest engine option, the Scripps 302 V-12.
sierraboat.com
Larry
Ries
Diamond
- Joined
- Mar 15, 2004
- Location
- Edison Washington USA
I would pull these on my hossfeld bender. Especially since you need those long straight sections. Not a rolling job, in my opinion. The edge bending die set for the hossfeld would do this, but you would need custom die blocks to support the half oval section, as the standard dies are for flat bar. But those could, again, be made from UHMW. Maybe even particle board. Figure 11 on this page shows a steel flat bar being bent the hard way on a hossfeld. https://www.hossfeldbender.com/tooling/handrail-capping-emt-square-tube/
Bending, in general, is kinda specialized. I have been bending things since the late 70s on my hossfeld, and still have a lot to learn.
Bending, in general, is kinda specialized. I have been bending things since the late 70s on my hossfeld, and still have a lot to learn.
The one I'm working on is a 22' version of that one, pretty much the same thing. No reproduction parts available for these things.I suppose boat parts are best made of brass or stainless and brass is easier to work. It is easy to silver braze straight pieces to the quarter circle pieces.
1937 Gar Wood 25ft Triple Cockpit - "Midnight Thunder" - Sierra Boat Co.
1937 Gar Wood 25ft Triple Cockpit. Midnight Thunder is one of only three 25-footers equipped with the largest engine option, the Scripps 302 V-12.
Larry
A quick gooogle search and everything I could find on bending the hard way was being rolled, which is why I was thinking that way and why my original question was geared that way. I have a roller, but I also have a model 32 JD2 bender. I am going to have to make dies for either one. You think that spending my time on dies for the bender might be a better use of my time? The pieces I have to make are not a constant radius, the shape changes as you go around the corner and the legs are not perfectly straight either, but the shape there doesn't bother me too much.
I looked and the brass I ordered is 360, good for machining but not so much for forming. Looks to be the only stuff available in the shape I need though.
Ries
Diamond
- Joined
- Mar 15, 2004
- Location
- Edison Washington USA
In the middle of the night, when I couldnt sleep, this popped into my head.
And now, my opinion is that I would absolutely bend em from flat bar, not premade oval.
Since I have one, my first choice would be the hossfeld, which will edge bend flat bar the hard way.
But since I also have one, I could also roll em with the 3 roll section bender, just being careful on start and stop points to get the bend in the middle of the part.
In either case, I might have to manually tweak the bend, I do this is a large vise that is bolted to a post that is bolted to the concrete floor.
I use either a 3 foot piece of pipe big enough to slip over the flat bar, or a 24" crescent wrench that hangs on that vise.
Tune up the bend to be flat and in plane, to take out any twists, and to make sure its the proper degree of bend.
Then I would cut a piece of something like 3/4" mdf to the outside of the curve, drill the holes for the screws, and screw the brass bar down on the MDF, and hand sand the outside of the bar to the oval radius.
Me, I would use a 4 1/2" grinder with a flap disc on it, maybe 80 grit or so, alumina zirconia abrasive. After I got the oval pretty close, go over it with descending grits on a random orbit sander.
unscrew it from the MDF, and screw it onto another piece of MDF with the inside radius cut out, and sand that one. The amount of material you need to remove is pretty small, and its much easier to bend the rectangular bar than the half oval. Wear a respirator, you dont wanna breathe 360 dust- its got lead in it, along with copper and tin.
My section rolls came from Eagle- who happen to be right there in Alabama. If you have section rolls, (sometimes called angle rolls) use them. If all you have is plate rolls, call up Eagle, and see if they will either roll em for you, or recommend a customer in your area who bought rolls from them. By rolling the flat bar, you dont need custom rolls, just the standard rectangular set of rolls and shims.
Doing it this way is easier than my early ideas, or anything anyone else has posted here, as far as I am concerned.
www.eaglebendingmachines.com
And now, my opinion is that I would absolutely bend em from flat bar, not premade oval.
Since I have one, my first choice would be the hossfeld, which will edge bend flat bar the hard way.
But since I also have one, I could also roll em with the 3 roll section bender, just being careful on start and stop points to get the bend in the middle of the part.
In either case, I might have to manually tweak the bend, I do this is a large vise that is bolted to a post that is bolted to the concrete floor.
I use either a 3 foot piece of pipe big enough to slip over the flat bar, or a 24" crescent wrench that hangs on that vise.
Tune up the bend to be flat and in plane, to take out any twists, and to make sure its the proper degree of bend.
Then I would cut a piece of something like 3/4" mdf to the outside of the curve, drill the holes for the screws, and screw the brass bar down on the MDF, and hand sand the outside of the bar to the oval radius.
Me, I would use a 4 1/2" grinder with a flap disc on it, maybe 80 grit or so, alumina zirconia abrasive. After I got the oval pretty close, go over it with descending grits on a random orbit sander.
unscrew it from the MDF, and screw it onto another piece of MDF with the inside radius cut out, and sand that one. The amount of material you need to remove is pretty small, and its much easier to bend the rectangular bar than the half oval. Wear a respirator, you dont wanna breathe 360 dust- its got lead in it, along with copper and tin.
My section rolls came from Eagle- who happen to be right there in Alabama. If you have section rolls, (sometimes called angle rolls) use them. If all you have is plate rolls, call up Eagle, and see if they will either roll em for you, or recommend a customer in your area who bought rolls from them. By rolling the flat bar, you dont need custom rolls, just the standard rectangular set of rolls and shims.
Doing it this way is easier than my early ideas, or anything anyone else has posted here, as far as I am concerned.
Eagle Bending Machines | United States
Eagle is 100% American owned and has placed over 7,500 machines in North America. PROOF that our Section Bending Rolls, Profile Benders, CNC Benders and Service are truly valued by the metal fabrication industry. Our section Benders incorporate Features and Superior Quality not found on...
www.eaglebendingmachines.com
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richard newman
Titanium
- Joined
- Jul 28, 2006
- Location
- rochester, ny
I like Ries' idea! But being a woodworker, I'd modify a hss router bit to cut the oval halves, instead of sanding. If you get the curve on the mdf just right, you could use it as a template to profile the brass with a flush cutting bit, and then follow with the half oval. Rinse and repeat on the inside curve. Flip the template over for the left hand piece.
A lot of aircraft parts were made with pin routers and shapers, the cutting forces for thin aluminum are pretty modest and woodworking tools and techniques work just fine. 3/16" brass shouldn't be much of a problem, just avoid high rake cutters
A lot of aircraft parts were made with pin routers and shapers, the cutting forces for thin aluminum are pretty modest and woodworking tools and techniques work just fine. 3/16" brass shouldn't be much of a problem, just avoid high rake cutters
Eagle isn't far at all from me, looks like they just sell equipment but don't do any rolling. Their dies are not going to fit my roller. I have a lathe and could turn out some two piece dies pretty easily so will probably go that way. The profile of the trim is almost identical to a 1/2" radius, certinly close enough. A 1/2" quarter round bit in a big router set to the correct depth would give me the profile, and maybe if I'm lucky I can get a good enough finish that I don't have a ton of clean up to do. I've routed brass before, helps to slow the router down some and if you can keep the chatter out of it will give a decent finish. I have a pretty good size router, might have to try a little sample. If I can roll the right shape into the brass I should be able to use the brass as a pattern for inside and outside router guides and use those to cut the profile. Or I hope anyway. Would be really cool if I could get this to work the first time.
swarfless
Cast Iron
- Joined
- Aug 31, 2005
- Location
- South Australia
Fellas, I think (another one) there's a lot of overthinking going on. This is 3/4 x 3/16 BRASS right? I'd bend the buggers by hand over a wooden/MDF former. The former would be a made up sharp bottommed vee 'pulley', the vee opening into parallel sides 3/8 apart. Assuming the OP has the brass section in straight form, torch anneal two pieces (over-length, say a foot either side of the bend) just in the bend region, hold them back-to-back, (after thought: maybe tape them together with electricians' tape, full wrap). Now work them, that is simply bend, in the 'pulley' till they resist. Re-anneal & repeat. The final working should leave them hard enough for purpose. Do another pair, etc. The taping would be last-ditch, only if simple pairing did not offer enough support, a bit of a PITA re annealing. Annealing: heat to cherry red & water quench. Fully annealed brass is like butter, just darker.
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I think this is where I start. Low investment in terms of time and materials with the added advantage of being able to bend the brass over a form that is exactly the shape I want instead of having to match the shape with a roller or bender. A couple questions. Does the brass have to be quenched? I have to anneal about two feet of it, seems like the beginning will have cooled quite a bit by the time I get to the end. I'm guessing the brass is going to spring back some when I bend it so I will probably have to experiment some with my form?
L Vanice
Diamond
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- Feb 8, 2006
- Location
- Fort Wayne, IN
Annealing brass is just a matter of getting it to glow red. Avoid overheating. Cooling can be fast or slow, makes no difference. Fast cooling saves time. Severe forming may require re-annealing one or more times, after each time it gets hard to form.
Larry
Larry
swarfless
Cast Iron
- Joined
- Aug 31, 2005
- Location
- South Australia
